Conservative Management of Rectal Cancer With Local Excision and Adjuvant Therapy

Conservative Management of Rectal Cancer With Local Excision and Adjuvant Therapy

The article by Drs. Wagman and
Minsky is an excellent overview
of the history, indications, treatment considerations, and comparative results
of local excision alone and local excision plus chemoradiotherapy for selected
distal rectal cancers. Although the literature and experience with local
excision have increased, use of the technique has probably diminished over the
past decade, primarily due to the groundswell of publications that lionize total
mesorectal excision with low colorectal or coloanal anastomosis for most rectal
cancers, as well as our inability to stage and predict nodal involvement, even
in T1 cancers.

It is, therefore, natural for the young colorectal surgeon to
promote total or near-total rectal excision for anything but the tiniest, very
low rectal cancer. However, before signing up for a total mesorectal excision
and coloanal anastomosis, the patient with a somewhat larger, low cancer
requires a prolonged office visit to fully grasp all the issues at play here. To
be fair, the physician must describe not only the possible genitourinary side
effects of the surgerynowadays minimized, but not totally effaced, by careful
nerve-sparing surgerybut also the decreased time from defecational signals to
more urgent need. Additionally, the physician must portray the essential
ignorance of nodal status (and, thus, the specter of occult nodal involvement)
with anything but a total nodal excision.

Procedures to Perform Prior
to Local Excision

If the patient persists in considering local excision, several
options might further guide the decision:

A good transanal ultrasound exam and magnetic resonance
imaging with rectal coil can be used to look for transmural extension and
possible involved nodes.

If an enlarged node is seen, a transrectal ultrasound-guided
needle biopsy is worth considering.

If images record questionable or no transmural invasion, one
might proceed with a positron-emission tomography (PET) scan in search of hot
nodes.

Assuming no nodes are imaged by PET, a full-thickness disc
excision could be performed, with removal of the underlying mesorectum and lymph
nodes. (If attempting a sentinel node biopsy, use very little dye, since even 1
cc stains everything and is useless.) If a node or deep margin is positive, then
the decision for low anterior resection or abdominoperineal resection, probably
after preoperative chemoradiotherapy, is made. If a mucosal margin is
microscopically positive, a reexcisionand even re-reexcisionsof that
margin can be performed.

Data clearly show that patients with positive margins will not
have acceptable local control.[2] Is it harmful to perform reexcisions in an
attempt to provide clear mucosal margins? We have not found this to be so,
either for local control after local excision and chemoradiotherapy or after low
anterior or abdominoperineal resection following local excision attempts. With
the rectum, potency, and/or continence at stake, the patient will be more
satisfied if every viable alternative is explored prior to a very low anterior
or abdominoperineal resection.

Assessment Difficulties

Anecdotal cases of T3, NX, N0, and even N1 tumors have been
treated with local excision plus chemoradiotherapy. However, there have not been
enough cases to provide meaningful data regarding local or systemic control
rates.[1] Similarly, the authors list 33 of 58 cases of recurrence in which
long-term salvage was achieved by low anterior or abdominoperineal resection.
These data, however, were not prospectively collected, so the real salvage rate
is probably considerably less.

It is unlikely that a randomized trial of local excision vs low
anterior resection or abdominoperineal resection could ever be carried out,
because patients would not accept the more extensive extirpational procedures if
they thought the two therapies might actually be of equal value for a given
tumor. Clearly, certain cancers are best treated by local excision with or
without radiation therapy and others are best treated by abdominoperineal or low
anterior resection with or without radiation therapy. For a third group of
tumors, however, the preferred operative approach exists in a zone of
uncertainty. We must strive to correctly group our patients and to develop
techniques that will reduce the numbers of this third cohort.

Future Trials

To this end, we need to develop trials to help find
chemoradiotherapy regimens with more efficacy and less toxicity, as well as
trials looking for better staging techniques (eg, sentinel node biopsy, limited
lymphadenectomy with local excision, PET scanning). We have all noted complete
pathologic responses to chemoradiotherapy. One wonders if preoperative
chemoradiotherapy might improve tumor control with local excision procedures.
Potential dangers include poorer wound healing and the fact that the tumor site
may be overlooked after a major or complete response. To avoid the latter, the
tumor boundaries should be tattooed prior to instituting therapy.

Given our inability to complete trials of chemoradiotherapy
sequencing in this country, it is doubtful that we will be able to assess the
value of preoperative adjuvant therapy vs postoperative therapy in a phase III
trial. Furthermore, no staging method is as accurate as an intact surgical
specimen. Since there is no difference in the position of the small bowel before
and after transanal excision, the appeal of preoperative chemoradiotherapy in
this setting is not as great as it is prior to larger excisional procedures of
the rectum. Thus, the only theoretical advantage of preoperative (vs
postoperative) chemoradiotherapy is its 4- to 6-week earlier delivery.